Evaporating apparatus



Patented @cto 19, 19.26.

J'Cl'ilhl' GOLDENG, OF SI: NFZEL'B, ANT JUEN CHRISTOPHER STEAD, OE SHOREHAM- EY-Sl-EA, ENG-LAND, ASSIG-NGRQ 1'0 BECK) LIIVHTED, 01? LUHDOH, ENGLAND, A COB- ]?OR. TJION 01 BRITAIN.

nvnrolmrme APPARATUS.

Applteationfiled December 253 1925, Serial No. 77,027, and in Great Britain December 28, 1924.

ot the general character indicated which will enable the evaporation process to be controlled or regulated in a simple manner.

Further objects and advantages of inoproved apparatus in accordance with the invention will be apparent to those versed in the art from the tollowing description and the claims appended thereto.

the invention broadly stated resides in the provision of preheater arranged above the dryi'n ,r rolls and adapted to utilize the heat oi the steam or vapour resulting from evaporation of the liquid or tluid under treatment thereon in a simple and eli'icient manner. It is preferred to provide evaporating sheets or plates over the surfaces of which the liquid passes before reaching the rolls to increase the evaporative capacity of the apparatus, said sheets or plates being preferably heated by the steam or vapour ol the liquid under treatment.

The invention is more particularly pointed out in the appended claims.

In carrying our invention into practice a preheater is arranged above the ll-shaped space between a pair of rotatable stea1nheated rolls which are arranged side by side in the usual way; the liquid to be evaporated overflows from the said preheater on to evaporating surfaces (plates or sheets of any suitable section and shape) which deliver it upon the peripheries of the rolls; and the pro-heater and the said evaporating surtacos are enclosed by an outer casing or-hood which is open below and terminates at the top in an exhaust chamber. The vapour given olt during the evaporation on the rolls passes up between the walls or the pro-heater and the evaporating plates or sheets, bellies being provided for directing it alternately upon the sides of the pro-heater and the inner tacos ot the said plates or sheets in order to v wear from the exhaust chamber so that cut its of air of suitable velocity are caused to how up between the outer casing and the evaporating surfaces over which the liquid is flowing down.

Our invention is illustrated diagrammatically in the accompanying drawing; which it end elevation a pair of steam-heated l'Ol Er, a preheater 13 arranged above the i -shaped space between the said rolls, evaporating sheets C, C, on to which the liquid overflows from the said pro-heater, an outer casing ll which encloses the said reservoir and evaporating sheets, and anexhaust chamber E from which vapour and air are drawn oil by a tan or exhauster (not shown) through a pipe F.

'llie pie-heater l3 shown in the drawing is in the tor-n1 ot a deep narrow trough, into whiclii the liquid is introduced at the bottom of the trough through a supply pipe 5, and from which the liquid displaced upwards by the incoming cold teed overflows on to the evaporating sheets C, G, through pipes a, the overflow being regulated by controlling the supply so that an approximately uniform lihn ot the liquid flows down upon the outer faces of the said sheets. Suitable weirs may be provided in place of these pipes.

Fixed battles G are provided for deflecting the ascending vapour alternately upon the walls of the pre-heater and the inner faces of the evaporating sheets; and adjustable battles H are Jrovided for regulating the eliect ot' the suction created by the fan on the steam space between the pre-heater and the evaporating sheets, thus controlling the heating oi the liquid in the preheater and consequently to some extent the evaporation.

Suitable gutters, such as indicated at g, g, 9 are provided for collecting and carrying otl condensation water.

The heat radiated from the bare portions of the rolls, from which the dried product has been stripped, may be utilized to heat more or less the currents of air which pass up between the casing D and the outer faces "'un a predetermined preliminary heatof the evaporating sheets, the velocity of these currents being determined by the area of the cross section of the air passages or by the speed of the fan. The evaporative effect of counter-currents of air flowing over the descending films of liquid is considerable,' and this, in conjunction with the preliminary heating of the liquidin, thej,pr.e..

heater and the further transfer of heat units to it as it'flows over the heated evaporating .sheets, practically enables a second effect evaporation to be effected without substantiallyincreasing the cost of'the operation; further, owing to the shorter time'requlred to boil off the pre-heated and partially con- 7 centrated liquid on the steam heated surfaces of the rolls,-the dry product obtained is of better quality and appearance than that obtained heretofore.

We claim 1- p 1. Evaporating apparatus for evaporating a fluid substance at atmospheric pressure comprising steam-heated drying rolls, a preheater for said fluid substance arranged above said drying rolls, vapour directing means for directing vapour produced from the fluid on to the surface of said preheater.

'2. Evaporating apparatus for evaporating a fluid substance at atmospheric pressure comprising steam-heated drying rolls, a preheater for said fluid substance arranged above said drying rolls, vapour directing means for directing vapour produced from the fluid on to the surface of said preheater and means for conducting the fluid from said preheater on to said rolls.

3Evaporating apparatus as claimed in claim 2 wherein the means for conducting the fluid from said preheater on to the rolls comprise evaporating surfaces and means I for conducting the fluid from the preheater on to said surfaces. 7

- 4. Evaporating apparatus for evaporating a liquid substance at atmospheric pressure comprising steam-heated drylng rolls, a preheater for said liquid arranged above said 7 rolls, evaporating sheets forming a substantially enclosed space for heated vapour ris ing from said rolls about said preheater, means for conducting the liquid from the preheater after passage therethrough on to the outer surfaces ofsaid sheets whence the liquid flows down said surfaces and on to the said rolls.

5. Evaporating apparatus as claimed in claim 4 comprising also a hood spaced from the outer surfaces of said sheets and means for inducing the heated vapour rising from said rolls to flow up inside said sheets and for inducing a counter current of air to pass over the outer surfaces of said sheets.

said evaporating sheets, a hood spaced from but partially enclosing said sheets and a conduit through which air can be drawn over the evaporating surfaces of said sheets in the opposite direction from that in which the liquid flows thereover on its passage to the drying rolls.

In testimony whereof, we have signed this specification.

JOHN GOLDING. JOHN CHRISTOPHER STEAD. 

